For various reasons, it is often desirable to be able to locate a mobile phone. For example, the FCC (Federal Communication Commission) is now requiring wireless companies to accurately locate mobile 911 callers. Current location tracking methods provide a rough area in a cell at which the phone is located.
FIG. 1 shows a wireless phone network 100 having mobile phones (MP) 111-114 located within cells 101 and 102. Each cell includes a base station 105, 106, and as the mobile phones 111-114 travel they communicate with a closest base station. Using current technology, when location information for a mobile phone is requested via third party telephone 116, a mobile telephone service operator (MTSO) 115 searches for the cell that includes mobile phone. The MTSO 115 then requests the location information of mobile phone from the base station associated with the cell.
When a mobile phone is in standby mode and the phone is not activated, the mobile phone regularly sends a supervisory signal to the base station. Thus, the base station knows all phone numbers that are located in its own cell. This is referred to as a mobile phone registration. A similar registration procedure occurs when a call is activated within a cell. This registration specification helps the MTSO 115 know the cell location of the mobile phone.
When the third party telephone 116, in any location (whether in the same cell or not), asks the location of a mobile phone to MTSO 115 (e.g., via telephone line 118, Private Branch Exchange (PBX) 117, and line 121, MTSO 115 can provide certain location information after MTSO 115 finds the registration cell. The base station tracks mobile phones in its cell by the received signal strength. The cell radius is typically one to three miles.
As shown in FIG. 2, base station 220 has diversified antennas to communicate with mobile phones in the cell 200. The current location tracking methods can only provide a region 201-209 in the cell 200 of the location of the mobile phone. Current methods cannot provide a pinpoint location. Accordingly, a more granular location tracking method is needed.